Wireless communication system, wireless communication unit and method of synchronisation

Abstract

A method of synchronising a wireless communication unit in a communication system, the method comprising at said wireless communication unit the steps of: monitoring transmissions from a communication system and processing ( 400 ) frequency and/or timing information from the communication system. The method further includes the steps of transmitting ( 404 ) frequency and/or timing information by said wireless communication unit; receiving and processing ( 406 ) said frequency and/or timing information transmitted by said wireless communication unit at a receiving portion of said wireless communication unit. The wireless communication unit then compares frequency and/or timing information transmitted from the communication system to that transmitted by said wireless communication unit; and synchronises said wireless communication unit if said comparison step does not yield a match. A wireless communication unit and a communication system are also provided.

1 . A method of synchronising a wireless communication unit in a communication system, the method comprising at said wireless communication unit the steps of: 
 monitoring transmissions from a communication system;    processing frequency and/or timing information from the communication system;    the method characterised by the steps of:    transmitting frequency and/or timing information by said wireless communication unit;    receiving and processing said frequency and/or timing information transmitted by said wireless communication unit at a receiving portion of said wireless communication unit;    comparing frequency and/or timing information transmitted from the communication system to that transmitted by said wireless communication unit; and    synchronising said wireless communication unit if said comparison step does not yield a match.    
     
     
         2 . The method of synchronising according to  claim 1 , the method further comprising the step of: 
 transmitting a frequency and/or timing offset message from the receiving portion of said wireless communication unit to a transmitting portion of said wireless communication unit.    
     
     
         3 . The method of synchronising according to  claim 2 , wherein said frequency and/or timing offset message is sent via a RS-232 serial interface.  
     
     
         4 . The method of synchronising according to  claim 1 , wherein the step of comparing includes the step of calculating a frequency and/or timing offset that is required to synchronise the wireless communication unit to the communication system.  
     
     
         5 . The method of synchronising according to  claim 4 , wherein the step of calculating a frequency and/or timing offset, includes the step of: 
 comparing the calculated frequency and/or timing offset to a threshold value, and if said calculated frequency and/or timing offset exceeds said threshold value, adjusting a transmit portion of said wireless communication unit.    
     
     
         6 . The method of synchronising according to  claim 1 , wherein the step of transmitting frequency and/or timing information by said communicating unit transmission is made on a receive frequency of said wireless communication unit.  
     
     
         7 . The method of synchronising according to  claim 6 , wherein the step of transmitting frequency and/or timing information by said wireless communication unit is performed in one of the following: a signalling channel (SCH), a broadcast signalling channel (BSCH), a broadcast network channel (BNCH), a linearisation period in a traffic channel, or a common linearisation channel.  
     
     
         8 . The method of synchronising according to  claim 7 , wherein said communication system is a trunked radio communication system employing a TETRA protocol with the wireless communication unit being a repeater unit facilitating communication between the trunked radio communication system and a plurality of mobile stations.  
     
     
         9 . The method of synchronising according to  claim 8 , wherein the repeater unit synchronises transmissions between the trunked communication system and a second direct mode radio communication system, to facilitate the communication of at least one of the plurality of wireless communication units communicating in direct mode being passed to the trunked communication system.  
     
     
         10 . The method of synchronising according to  claim 1 , wherein said receiving portion of said wireless communication unit sends frequency and/or timing information to the transmit portion of said wireless communication unit prior to a transmission of frequency and/or timing information.  
     
     
         11 . The method of synchronising according to  claim 1 , the method further comprising the step of:  
       aligning a reference frequency and/or timing of the wireless communication unit to the communication system's frequency and/or timing, in response to the step of processing said communication system's frequency and/or timing.  
     
     
         12 . A wireless communication unit adapted to perform the synchronising steps of  claim 1 .  
     
     
         13 . A communication system adapted to perform the synchronising steps of  claim 1 .  
     
     
         14 . A storage medium storing processor-implementable instructions for controlling one or more processors to carry out the method of  claim 1 .  
     
     
         15 . A wireless communication unit comprising a transmitter transmitting frequency and/or timing information, the wireless communication unit characterised by: 
 a receiver, operably coupled to said transmitter, receiving frequency and/or timing information transmitted from said communication system and said frequency and/or timing information transmitted from said transmitter of said wireless communication unit; and    a processor, operably coupled to said receiver and said transmitter, processing said frequency and/or timing information and determining a frequency and/or timing offset between said frequency and/or timing information from said communication system and said transmitter, and informing said transmitter of said offset.    
     
     
         16 . The wireless communication unit according to  claim 15 , further characterised by: 
 comparison means operably coupled to said processor for determining said frequency and/or timing offset between said frequency and/or timing information from said communication system and said transmitter.    
     
     
         17 . The wireless communication unit according to  claim 16 , further characterised by: 
 adjustment means in the transmitter to synchronise said frequency and/or timing of the wireless communication unit if said comparison does not yield a match.    
     
     
         18 . The wireless communication unit according to  claim 15 , wherein the receiver forwards a frequency and/or timing offset message to said transmitter of said wireless communication unit via a RS-232 serial interface.  
     
     
         19 . The wireless communication unit according to  claim 17 , further comprising a memory element operably coupled to said processor wherein said memory element stores a threshold value to be used by the comparison means to determine whether the calculated frequency and/or timing offset exceeds said threshold value, and if said calculated frequency and/or timing offset exceeds said threshold value, said adjustment means adjusts said transmitter.  
     
     
         20 . The wireless communication unit according to  claim 15 , wherein said communication system is a trunked radio communication system employing a TETRA protocol and the wireless communication unit is a repeater unit facilitating communication between the trunked radio communication system and a plurality of mobile stations.  
     
     
         21 . The wireless communication unit according to  claim 15 , wherein said receiver forwards frequency and/or timing information to the transmitter prior to a transmission of frequency and/or timing information.  
     
     
         22 . A communication system adapted to include the wireless communication unit of  claim 15.